Turbochargers are a type of forced induction system. They compress the air flowing into an engine, thus boosting the engine's horsepower without significantly increasing weight. Turbochargers use the exhaust flow from the engine to spin a turbine, which in turn drives an air compressor. Since the turbine spins about 30 times faster than most car engines and it is hooked up to the exhaust, the temperature in the turbine is very high. Additionally, due to the resulting high velocity of flow, turbochargers are subjected to noise and vibration. Such conditions can have a detrimental effect on the components of the turbocharger, particularly on the rotating parts such as the turbine rotor, which can lead to failure of the system.
Swirling and/or turbulent flow of the exhaust gases into the turbine rotor increases the problems associated with noise, vibration and harshness. Exhaust gases entering the inlet of the turbine of a turbocharger in automotive and other applications pass through various bends and restrictions in the exhaust manifold. These restrictions and bends cause the exhaust gases to be turbulent and/or swirling, resulting in less than optimum efficiency or performance of the turbine of the turbocharger. Further, due to the turbine rotor or wheel rotation, incoming gases can swirl in the same direction as the rotation of the rotor adding to its inefficiency.
An attempt to address the above described drawbacks was made in U.S. Pat. No. 7,089,963 to Meheen through the use of a “flow laminarizing device.” The Meheen device is shown in FIGS. 1 and 2 and includes a plurality of tubes 102, which define a single cluster 104. Each of the tubes 102 has a wall 106, defining a passageway 108 that allows fluid flow. Each passageway 108 has a length L and a cross-sectional area A. The Meheen device 100B has retaining arms 110 that support the device in a fixed position. Fluid laminarizing and fluid drag can be controlled in the Meheen device 100B through the variation of the number, size and wall roughness of the tubes 102.
However, the Meheen device is a relatively complex, separate structure that increases cost and requires installation. The Meheen device suffers from the drawback of its own deterioration over time, which can increase the potential for foreign object damage if a portion of the device becomes separated from the cluster 104 and impacts the turbine rotor. This is especially a problem where the cluster 104 is formed from individual components such as tubes 102 and retaining arms 110 that are welded together or otherwise bonded, which may over time break apart given the high stress environment where the device is situated.
Thus, there is a need for a flow control or direction system at the inlet of a turbine that is effective at reducing or eliminating turbulent flow and/or swirl. There is a further need for such a system that is cost effective and dependable.